However, Google has denied any relation to Panda or Penguin, and initial indications seem to discount any connection to Google's recently-sent mobile UX webmaster warnings.

Now, thanks to research by SearchMetrics, we may have another piece of the puzzle to scratch our heads over.

The search analytics company discovered that the update seems mostly to have affected "e-commerce and keywords with measurable CPC", with the biggest fluctuations happening for "retailers, shops, price comparison etc."

If we can pin down a reason for this update, based on SearchMetrics' data, it's that Google is attempting to 'clean up' e-Commerce brand-related searches. For instance, SearchMetrics discovered an interesting tendency for misspellings of brand keywords (such as 'addidas') to bring up similar results as their correctly-spelled counterparts.

Marcus Tober, SearchMetrics founder, wrote:

"Before the recent change, mostly price comparison sites, shops and small ad sites ranked here. Then Google started to treat the keywords equally as brands. “As usual” the brand ranked on position 1 with Wikipedia right behind – which represents the typical search results for a brand."

SearchMetrics pointed out that it is too early to carry out any kind of winner/loser analysis, as it seems the fluctuations are still happening. But it did say that it noticed very heavy fluctuations for some 'traffic-heavy' keywords, writing: "They appear on position 1, then 5 to 9 and then completely vanish."